In a communication system a communication network is provided, which can connect two communication terminals so that the terminals can send information to each other in a call or other communication event. Information may include voice, text, images or video.
One such communication system is a peer to peer communication system, in which a plurality of end users can be connected for communication purposes via a communications structure such as the internet using peer to peer client software. The communications structure is substantially decentralised with regard to communication route switching therein for connecting the end users. That is, the end users can establish their own communication routes through the structure based on exchange of one or more authentication certificates (user identity certificates—UIC) to acquire access to the structure. The structure includes an administration arrangement issuing the certificates to the end users. Such a communication system is described in WO 2005/009019.
Peer-to-peer communications are beneficial to the user as they are often of significantly lower cost than traditional communication networks, such as fixed line or mobile networks. This may particularly be the case for long distance calls. These systems may utilise voice over internet protocol (“VoIP”) over an existing network (e.g. the Internet) to provide these services, although alternative protocols can also be used.
In a communication system, such as a peer to peer system, client software is installed on an end user device such as a personal computer (PC) to allow the end user to communicate via the communications network and to identify the user within the communication network. The user interface of the client software can be controlled by the client to display user facilities and to indicate events occurring, such as an incoming call. FIG. 1A is a diagram of an end user device 10 running client software to communicate directly with the peer to peer system. The client software comprises a user interface layer 12, a client engine layer 14, and a protocol layer. The protocol layer is arranged to handle the communication between the client engine and the peer to peer system 104.
Users may be accustomed to mobility whilst using conventional telephony services, due to the prevalence of cordless phones and mobile cellular networks. It is therefore desirable to run the client software on mobile devices such as a mobile phone or other battery operated cordless device. However, running the client software on a mobile end user device presents a number of problems. Hand held mobile devices are typically battery operated and have less CPU resource than a PC. The power requirement used to run the client software to handle the communications can reduce the battery life considerably for battery operated devices. Furthermore, running the client software on the user device may use valuable CPU resources that are required to run other applications on the device.
One further problem caused by using a mobile device in an VoIP communication system is that in a VoIP system such as a peer to peer system, it is necessary to be constantly connected to the internet in order to be notified of communication events, such as receiving a call. Maintaining a constant connection between the communication network and the internet is not only an inefficient use of battery life and CPU resources of the device, but also an inefficient use of network connection resources. Also being constantly connected to the internet may be costly for a user. Furthermore the quality of the connection to the internet may be poor therefore degrading the quality of the communication.